Abstract
Keywords - Hydrogen Engine, Optical Engine, 3D CFD Simulation, High-pressure Direct Injection, Efficiency
The BMW Group Research and Technology has been collaborating with the Institute for Internal Combustion Engines and Thermodynamics at Graz University of Technology for many years on the continued development of hydrogen combustion processes using internal mixture formation. This has involved particularly investigations of the possibilities and challenges associated with the application of high pressure direct injection. The objective is development of H2 combustion processes applicable to vehicles, having the highest possible efficiency and a power density superior to modern day passenger car gasoline and diesel engines.
Progress in the area of combustion process development relating to direct injection of hydrogen will be documented on the basis of simulation and experimental results. In particular we present a closed-loop development process methodology involving "3D CFD simulation - optical measurements - single cylinder research engine trials" illustrated by actual examples and results.
The 3D CFD method can be used for both mixture formation and combustion simulation, and offers significant insights regarding promising designs for jet and piston geometries. Experimental investigations on a research engine with an optically accessible combustion chamber then permit more precise validation of the numerical models used. Measurements on a thermodynamic research engine ultimately yield more detailed results regarding efficiency, emissions and specific power.
The characteristics of differing concepts are compared using geometrically different combustion chamber and injector jet designs by way of illustration. This yields in some instances substantial differences between wall heat losses and conversion rate for example, with a consequent direct effect on the achievable efficiency.